Voltage regulator module

ABSTRACT

A voltage regulator module includes a first circuit board, a switching circuit and a second circuit board. The switching circuit is disposed on a first surface of the first circuit board. A first contact pad is disposed on a second surface of the first circuit board. The switching circuit is connected with the contact pad through a conductive hole of the first circuit board. A first surface of the second circuit board is in contact with the first surface of the first circuit board. The first surface of the second circuit board includes a second contact pad. The second contact pad is fixed on the corresponding first contact pad. A second surface of the second circuit board includes a conductive pad. The conductive pad is connected with the corresponding second contact pad through a conductive hole of the second circuit board. The conductive pad is connected with a system board.

FIELD OF THE INVENTION

The present disclosure relates to a voltage regulator module, and moreparticularly to a voltage regulator module with reduced thickness.

BACKGROUND OF THE INVENTION

Please refer to FIGS. 1A and 1B. FIG. 1A schematically illustrates thestructure of a conventional electronic device. FIG. 1B schematicallyillustrates the structure of a voltage regulator module of theelectronic device as shown in FIG. 1A. As shown in FIGS. 1A and 1B, theelectronic device 1 has a horizontal layout structure. The electronicdevice 1 includes a central processing unit (CPU) 11, a voltageregulator module 12 and a system board 13. The voltage regulator module12 includes an output capacitor 14. The voltage regulator module 12 isused for converting an input voltage into a regulated voltage andproviding the regulated voltage to the central processing unit 11. Thevoltage regulator module 12 and the central processing unit 11 aredisposed on a first surface of the system board 13. For meeting the loaddynamic switching requirements, the output terminal of the voltageregulator module 12 is located near the input terminal of the centralprocessing unit 11. The output capacitor 14 is disposed on a secondsurface of the system board 13. The first surface and the second surfaceof the system board 13 are opposed to each other. The output capacitor14 is located beside the input terminal of the central processing unit11.

The voltage regulator module 12 further includes a circuit board 15 anda magnetic element 16. The magnetic element 16 is disposed on thecircuit board 15. Moreover, a switch element is disposed in a vacantspace between the circuit board 15 and the magnetic element 16. Thecircuit board 15 is disposed on the first surface of the system board13. The heat from the voltage regulator module 12 can be transferred tothe system board 13 through the circuit board 15. Moreover, the heat isdissipated away through a heat dissipation mechanism (not shown) of thesystem board 13.

However, according to the requirements, the power density for the systemboard 13 is gradually increased and the thickness for the system board13 is gradually decreased. Consequently, the voltage regulator module 12are developed toward small thickness (e.g., smaller than 5 mm, orsmaller than or equal to 3 mm). Since the switch element and themagnetic element 16 are disposed on the circuit board 15 of theelectronic device 1 according to the conventional technology, thethickness of the voltage regulator module 12 is still large. Moreover,for meeting the requirements of the multi-phase buck circuit, thecircuit board of the conventional voltage regulator module 12 is amultilayered circuit board and a plurality of planar winding assembliesare mounted in the multilayered circuit board. However, the use of themultilayered circuit board increases the thickness of the electronicdevice 1.

Therefore, there is a need of providing an improved voltage regulatormodule in order to overcome the drawbacks of the conventionaltechnologies.

SUMMARY OF THE INVENTION

An object of the present disclosure provides a voltage regulator modulewith reduced thickness.

In accordance with an aspect of the present disclosure, a voltageregulator module is provided. The voltage regulator module is disposedon a system board. The voltage regulator module includes a first circuitboard, at least one switching circuit and a second circuit board. Thefirst circuit board includes a first surface and a second surface. Thefirst surface and the second surface of the first circuit board areopposed to each other. At least one first contact pad is disposed on thesecond surface. The at least one first contact pad is served as at leastone of a positive output terminal, a negative output terminal and apositive input terminal of the voltage regulator module. The at leastone switching circuit is disposed on the first surface of the firstcircuit board. The at least one switching circuit is electricallyconnected with the at least one first contact pad through at least oneconductive hole of the first circuit board. The second circuit boardincludes a first surface and a second surface. The first surface and thesecond surface of the second circuit board are opposed to each other.The first surface of the second circuit board is located beside and incontact with the second surface of the first circuit board. The firstsurface of the second circuit board includes at least one second contactpad. The second surface of the second circuit board includes at leastone conductive pad. The at least one second contact pad is fixed on andelectrically connected with the corresponding first contact pad. The atleast one conductive pad is electrically connected with thecorresponding second contact pad through at least one conductive hole ofthe second circuit board. The at least one second contact pad is servedas at least one of the positive output terminal, the negative outputterminal and the positive input terminal of the voltage regulatormodule. The at least one conductive pad is served as at least one of thepositive output terminal, the negative output terminal and the positiveinput terminal of the voltage regulator module.

The above contents of the present disclosure will become more readilyapparent to those ordinarily skilled in the art after reviewing thefollowing detailed description and accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A schematically illustrates the structure of a conventionalelectronic device;

FIG. 1B schematically illustrates the structure of a voltage regulatormodule of the electronic device as shown in FIG. 1A;

FIG. 2 is a schematic perspective view illustrating the structure of avoltage regulator module according to a first embodiment of the presentdisclosure;

FIG. 3 is a schematic exploded view illustrating the structure of thevoltage regulator module as shown in FIG. 2;

FIG. 4 is a schematic perspective view illustrating the structure of thevoltage regulator module and taken along another viewpoint;

FIG. 5 is a schematic equivalent circuit diagram illustrating thevoltage regulator module as shown in FIG. 2;

FIG. 6 is a schematic perspective view illustrating the structure of avoltage regulator module according to a second embodiment of the presentdisclosure;

FIG. 7 is a schematic exploded view illustrating the structure of thevoltage regulator module as shown in FIG. 6;

FIG. 8 is a schematic perspective view illustrating the structure of avoltage regulator module according to a third embodiment of the presentdisclosure;

FIG. 9 is a schematic exploded view illustrating the structure of thevoltage regulator module as shown in FIG. 8 and taken along anotherviewpoint;

FIG. 10 is a schematic perspective view illustrating the structure of avoltage regulator module according to a fourth embodiment of the presentdisclosure;

FIG. 11 is a schematic exploded view illustrating the structure of thevoltage regulator module as shown in FIG. 10 and taken along anotherviewpoint;

FIG. 12 is a schematic perspective view illustrating the structure of avoltage regulator module according to a fifth embodiment of the presentdisclosure;

FIG. 13 is a schematic exploded view illustrating the structure of thevoltage regulator module as shown in FIG. 12;

FIG. 14 is a schematic exploded view illustrating the structure of avoltage regulator module according to a sixth embodiment of the presentdisclosure;

FIG. 15 is a schematic exploded view illustrating the structure of thevoltage regulator module as shown in FIG. 14 and taken along anotherviewpoint;

FIG. 16 is a schematic exploded view illustrating the structure of avoltage regulator module according to a seventh embodiment of thepresent disclosure; and

FIG. 17 is a schematic exploded view illustrating the structure of thevoltage regulator module as shown in FIG. 16 and taken along anotherviewpoint.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present disclosure will now be described more specifically withreference to the following embodiments. It is to be noted that thefollowing descriptions of preferred embodiments of this disclosure arepresented herein for purpose of illustration and description only. It isnot intended to be exhaustive or to be limited to the precise formdisclosed.

Please refer to FIGS. 2, 3, 4 and 5. FIG. 2 is a schematic perspectiveview illustrating the structure of a voltage regulator module accordingto a first embodiment of the present disclosure. FIG. 3 is a schematicexploded view illustrating the structure of the voltage regulator moduleas shown in FIG. 2. FIG. 4 is a schematic perspective view illustratingthe structure of the voltage regulator module and taken along anotherviewpoint. FIG. 5 is a schematic equivalent circuit diagram illustratingthe voltage regulator module as shown in FIG. 2. The voltage regulatormodule 2 may be disposed in an electronic device and welded on a systemboard or a carrier board (not shown) within the electronic device. Thevoltage regulator module 2 includes at least two single-phase buckcircuits, at least one input capacitor Cin and an output capacitor Cout.In some other embodiments, the buck circuits are replaced by boostcircuits or buck-boost circuits.

As shown in FIG. 5, the voltage regulator module 2 includes foursingle-phase buck circuits. Each single-phase buck circuit includes adriver switching unit 21 (also referred as a switching circuit 21) andan inductor L. The switching circuit 21 includes a driver and a switchelement. In other words, the voltage regulator module 2 includes fourswitching circuits 21 and four inductors L.

The second terminal of each switching circuit 21 and the first terminalSW of the corresponding inductor L are electrically connected with eachother to define the corresponding single-phase buck circuit. The firstterminals of the four single-phase buck circuits (e.g., the firstterminals of the switching circuits 21) are connected with each otherand electrically connected with the input capacitor Cin. The foursingle-phase buck circuits are connected with each other in parallel todefine a four-phase buck circuit. The input side of the voltageregulator module 2 includes a positive input terminal Vin+ and anegative input terminal Vin−. The first terminal of the input capacitorCin is electrically connected with the positive input terminal Vin+ ofthe voltage regulator module 2. The second terminal of the inputcapacitor Cin is electrically connected with the negative input terminalVin− of the voltage regulator module 2. The second terminals of the foursingle-phase buck circuits (i.e., the second terminals of the inductorsL) are connected with each other and electrically connected with theoutput capacitor Cout. The output side of the voltage regulator module 2includes a positive output terminal Vo+ and a negative output terminalVo−. The negative input terminal Vin− and the negative output terminalVo− are electrically connected with each other. The first terminal ofthe output capacitor Cout is electrically connected with the positiveoutput terminal Vo+ of the voltage regulator module 2. The secondterminal of the output capacitor Cout is electrically connected with thenegative output terminal Vo− of the voltage regulator module 2.

In an embodiment, each switching circuit 21 includes a switch and adriver for driving the switch. Moreover, the voltage regulator module 2further includes a control circuit 22. After the control circuit 22samples the output voltage of the voltage regulator module 2 and theoutput current of each single-phase buck circuit, the control circuit 22generates four pulse width modulation signals PWM1, PWM2, PWM3 and PWM4.The phase difference between every two adjacent pulse width modulationsignals is 90 degree. For example, the phase difference between thepulse width modulation signals PWM1 and PWM2 is 90 degree, the phasedifference between the pulse width modulation signals PWM2 and PWM3 is90 degree, the phase difference between the pulse width modulationsignals PWM3 and PWM4 is 90 degree, and the phase difference between thepulse width modulation signals PWM4 and PWM1 is 90 degree. Everysingle-phase buck circuit is controlled by the control circuit 22according to the corresponding pulse width modulation signal. Forexample, the first single-phase buck circuit is controlled according tothe first pulse width modulation signal PWM1, the second single-phasebuck circuit is controlled according to the second pulse widthmodulation signal PWM2, the third single-phase buck circuit iscontrolled according to the third pulse width modulation signal PWM3,and the fourth single-phase buck circuit is controlled according to thefourth pulse width modulation signal PWM4.

Structurally, the voltage regulator module 2 includes a first circuitboard 3, at least one metallic winding assembly 4 and a magnetic coreassembly 5. The first circuit board 3 includes a first surface 31, asecond surface 32 and at least one accommodation space 33. For showingthe position of the accommodation space 33, the first surface 31 and thesecond surface 32 as shown in FIGS. 2 and 3 are shown as two separatecomponents. In fact, the first surface 31 and the second surface 32 ofthe first circuit board 3 are integrally formed. The first surface 31and the second surface 32 are opposed to each other. Moreover, the firstsurface 31 of the first circuit board 3 includes at least one firstopening 311, and the second surface 32 of the first circuit board 3includes at least one second opening 321. As shown in FIG. 3, the firstsurface 31 of the first circuit board 3 includes four first openings311, and the second surface 32 of the first circuit board 3 includesfour second openings 321. The second openings 321 are aligned with thecorresponding first openings 311, respectively. In this embodiment, thefirst circuit board 3 includes four accommodation spaces 33. Theaccommodation spaces 33 are disposed within the first circuit board 3and arranged between the first surface 31 and the second surface 32. Theaccommodation spaces 33 are in communication with the correspondingfirst openings 311 and the corresponding second openings 321,respectively.

As shown in FIG. 3, the voltage regulator module 2 includes fourmetallic winding assemblies 4. The four metallic winding assemblies 4are wound along the same direction. Each metallic winding assembly 4 ismade of copper, aluminum, copper alloy, aluminum alloy or any otherappropriate metallic material with high conductivity and low parasiticresistance. The metallic winding assemblies 4 are disposed within thecorresponding accommodation spaces 33, respectively. That is, themetallic winding assemblies 4 are embedded in the first circuit board 3.Especially, the metallic winding assemblies 4 are arranged along aplane, which is parallel with the first surface 31 and the secondsurface 32 of the first circuit board 3. Moreover, each metallic windingassembly 4 includes a third opening 41. The position and shape of eachthird opening 41 match the positions and shapes of the correspondingsecond opening 321 and the corresponding first opening 311. For example,the third opening 41 is defined by an inner wall 44 of the correspondingmetallic winding assembly 4.

The magnetic core assembly 5 includes an upper core 51, a lower core 52and at least one lateral leg 53. The upper core 51 is disposed on thefirst circuit board 3 through the first surface 31 of the first circuitboard 3. Preferably but not exclusively, the upper core 51 is located ata middle region of the first circuit board 3. The lower core 52 isdisposed on the first circuit board 3 through the second surface 32 ofthe first circuit board 3. The upper core 51 and the lower core 52 aredisposed on two opposite sides of the first circuit board 3 and alignedwith each other. In this embodiment, the magnetic core assembly 5includes four lateral legs 53, and the four lateral legs 53 are arrangedbetween the upper core 51 and the lower core 52. In the embodiment asshown in FIG. 3, the four lateral legs 53 are connected with the lowercore 52. Alternatively, the four lateral legs 53 are connected with theupper core 51, or the four lateral legs 53 are individually arrangedbetween the upper core 51 and the lower core 52.

When the upper core 51 and the lower core 52 of the magnetic coreassembly 5 are connected with each other, the lateral legs 53 arepenetrated through the corresponding second openings 321, thecorresponding third openings 41 and the corresponding first openings311, respectively. Consequently, the first circuit board 3 is clampedbetween the upper core 51 and the lower core 52. In this embodiment, themetallic winding assemblies 4 are aligned with the corresponding laterallegs 53, respectively. Consequently, the magnetic core assembly 5 andthe metallic winding assemblies 4 are collaboratively formed as fourinductors L. Moreover, the directions of the DC magnetic fluxes flowingthrough the four lateral legs 53 are identical.

As mentioned above, the metallic winding assemblies 4 are embedded inthe corresponding accommodation spaces 33 of the first circuit board 3,and the magnetic core assembly 5 is disposed on the first circuit board3 in a vertical clamping manner. Moreover, one inductor L is defined bythe magnetic core assembly 5 and the corresponding metallic windingassembly 4. In other words, a portion of the inductor L (i.e., themetallic winding assembly 4) is disposed within the first circuit board3, and the other portion of the inductor L (i.e., the magnetic coreassembly 5) is disposed on the first circuit board 3. As previouslydescribed, the magnetic element of the voltage regulator module isstacked on the circuit board of the electronic device according to theconventional technology. Since a portion of the voltage regulator moduleis embedded in the circuit board according to the technology of thepresent disclosure, the height of the voltage regulator module islargely reduced.

Moreover, the metallic winding assemblies 4 are disposed within thecorresponding accommodation spaces 33 of the first circuit board 3.Consequently, the voltage regulator module 2 can meet the requirement ofthe multi-phase buck circuit. As mentioned above, the circuit board ofthe conventional voltage regulator module is a multilayered circuitboard and a plurality of planar winding assemblies are mounted in themultilayered circuit board. Consequently, the voltage regulator module 2of the present disclosure is much thinner than the conventional voltageregulator module. Since the metallic winding assembly 4 has lowerparasitic resistance and lower power loss than the planar windingassembly, the overall parasitic resistance and the overall power loss ofthe voltage regulator module 2 are reduced when compared with theconventional voltage regulator module.

As mentioned above, the voltage regulator module 2 further includes atleast one switching circuit 21 (e.g., four switching circuits). The fourswitching circuits 21 are disposed on the first surface 31 of the firstcircuit board 3. Two of the four switching circuits 21 are locatedbeside a first side of the upper core 51 and arranged along the samedirection. The other two of the four switching circuits 21 are locatedbeside a second side of the upper core 51 and arranged along the samedirection. The first side and the second side of the upper core 51 areopposed to each other. Consequently, the pins of the two switchingcircuits 21 located beside the first side of the upper core 51 areprotruded along the same direction, and the pins of the two switchingcircuits 21 located beside the second side of the upper core 51 areprotruded along the same direction.

The first circuit board 3 further includes at least one conductive hole(not shown). The conductive hole is a blind hole, e.g., a laser-drilledblind hole or a machine-drilled blind hole. The conductive hole is incommunication with the first surface 31 of the first circuit board 3 andthe corresponding metallic winding assembly 4. Each switching circuit 21is electrically connected with the first terminal 42 of thecorresponding metallic winding assembly 4 through the correspondingconductive hole.

In some other embodiments, the switching circuit 21 is embedded in thefirst circuit board 3 (not shown). The projection region of theswitching circuit 21 on the first surface 31 of the first circuit board3 and the projection region of the corresponding accommodation space 34on the first surface 31 of the first circuit board 3 are partiallyoverlapped with each other. In other words, the projection region of theswitching circuit 21 on the first circuit board 3 and the projectionregion of the corresponding metallic winding assembly 4 on the firstsurface 31 of the first circuit board 3 are partially overlapped witheach other. Preferably but not exclusively, the overlapped area is theminimum area of the conductive hole for resulting in the electricconnection between the corresponding switching circuit 21 and thecorresponding metallic winding assembly 4. Consequently, the conductivehole is connected with the corresponding switching circuit 21 and thecorresponding metallic winding assembly 4 through the conductive holealong the shortest path.

The magnetic core assembly 5 further includes a middle post 54. Themiddle post 54 is penetrated through the first circuit board 3. Forallowing the middle post 54 to be penetrated through the first circuitboard 3, a first middle perforation is defined by the four metallicwinding assemblies 4 according to the positions and shapes of the fourmetallic winding assemblies 4. Moreover, a second middle perforation isformed on the first surface 31 of the first circuit board 3, and a thirdmiddle perforation is formed on the second surface 32 of the firstcircuit board 3. The positions and shapes of the second middleperforation and the third middle perforation match the position andshape of the first middle perforation. After the middle post 54 ispenetrated through the third middle perforation, the first middleperforation and the second middle perforation, the middle post 54 isarranged between the upper core 51 and the lower core 52 and the fourlateral legs 53 are arranged around the middle post 54.

In some embodiments, a top end of the middle post 54 is connected with amiddle region of the upper core 51, and an air gap is formed between abottom end of the middle post 54 and the lower core 52.

In some other embodiments, the bottom end of the middle post 54 isconnected with a middle region of the lower core 52, and an air gap isformed between the top end of the middle post 54 and the upper core 51.

In some other embodiments, the magnetic core assembly 5 omits middlepost, and the first surface 31 and the second surface 32 of the firstcircuit board 3 omit the middle perforations, respectively. Under thiscircumstance, the middle regions of the first surface 31 and the secondsurface 32 are clearance regions for placing electronic components,planar winding assemblies or conductive traces. In one embodiment, noelectronic components, planar winding assemblies or electric traces arelocated at the clearance region.

In this embodiment, the first circuit board 3 includes a plurality oflateral walls 36. The plurality of lateral walls 36 are arranged betweenthe first surface 31 and the second surface 32 of the first circuitboard 3 and arranged around the first surface 31 and the second surface32 of the first circuit board 3. Moreover, the accommodation spaces 33are enclosed by the plurality of lateral walls 36. In anotherembodiment, at least one accommodation spaces 33 is exposed to at leastone lateral wall 36. Since the metallic winding assemblies 4 aredisposed within the corresponding accommodation spaces 33, the metallicwinding assembly 4 can be exposed to the corresponding lateral wall 36through the corresponding accommodation space 33. Consequently, the sizeof the metallic winding assembly 4 to be embedded in the first circuitboard 3 can be increased. In such way, the available space of thevoltage regulator module 2 is enhanced, and the DC equivalent resistanceof the metallic winding assembly 4 is reduced.

Moreover, since the DC magnetic fluxes of the middle post 54 aresuperposed and the AC magnetic fluxes are balanced out, the core loss isreduced. In some embodiments, the material of the middle post 54 isdifferent from the material of the lateral post 53. For example, themiddle post 54 is made of iron powder material with high saturationmagnetic density. Consequently, the cross section area of the middlepost 54 is reduced. In such way, the area of the metallic windingassembly 4 is increased, and the equivalent DC impedance and the powerloss of the voltage regulator module 2 are reduced.

Please refer to FIG. 4 again. The voltage regulator module 2 furtherincludes a first positive output contact pad 71, at least one firstnegative output contact pad 72, at least one first positive inputcontact pad 73 and a plurality of first signal contact pads 74. Thefirst positive output contact pad 71, the at least one first negativeoutput contact pad 72, the at least one first positive input contact pad73 and the plurality of first signal contact pads 74 are disposed on thesecond surface 32 of the first circuit board 3. Consequently, the firstpositive output contact pad 71, the at least one first negative outputcontact pad 72, the at least one first positive input contact pad 73 andthe plurality of first signal contact pads 74 are used as the positiveoutput terminal Vo+, the negative output terminal Vo−, the positiveinput terminal Vin+ and the signal terminals of the voltage regulatormodule 2, respectively. Since the negative output terminal Vo− and thenegative input terminal Vin− of the voltage regulator module 2 aredirectly connected with each other, the at least one first negativeoutput contact pad 72 can also be used as the negative input terminalVin−.

Preferably but not exclusively, the first positive output contact pad71, the at least one first negative output contact pad 72, the at leastone first positive input contact pad 73 and the plurality of firstsignal contact pads 74 have circular shapes, rectangular shapes, squareshapes, oval shapes or hollow rectangular shapes. The first circuitboard 3 further includes at least one conductive hole (not shown). Theconductive hole is a blind hole, e.g., a laser-drilled blind hole or amachine-drilled blind hole. The conductive hole is in communication withthe second surface 32 and the corresponding accommodation space 33 ofthe first circuit board 3. The at least one first positive input contactpad 73 is electrically connected with the second terminal 43 of themetallic winding assembly 4 through the corresponding conductive hole.Moreover, the heat generated by the metallic winding assembly 4 can betransferred to the second surface 32 of the first circuit board 3through the conductive hole. The voltage regulator module 2 furtherincludes at least one input capacitor 70. The at least one inputcapacitor 70 is disposed on the second surface 32 of the first circuitboard 3 and arranged between the at least one first positive inputcontact pad 73 and the at least one first negative output contact pad72. Moreover, the at least one input capacitor 70 is electricallyconnected with the at least one first positive input contact pad 73 andthe at least one first negative output contact pad 72 through the tracesof the first circuit board 3.

In the above embodiment, the voltage regulator module 2 is applied tothe four single-phase buck circuits. It is noted that the applicationsof the voltage regulator module are not restricted and may be applied totwo-phase buck circuit or multi-phase buck circuit.

Please refer to FIGS. 6 and 7. FIG. 6 is a schematic perspective viewillustrating the structure of a voltage regulator module according to asecond embodiment of the present disclosure. FIG. 7 is a schematicexploded view illustrating the structure of the voltage regulator moduleas shown in FIG. 6. In comparison with the first embodiment, the voltageregulator module 2 a includes two single-phase buck circuits. Thevoltage regulator module 2 of FIGS. 2 to 4 comprises four single-phasebuck circuits. In this embodiment, voltage regulator module 2 acomprises two-phase buck circuit.

Structurally, the voltage regulator module 2 a includes a first circuitboard 3, two metallic winding assemblies 4, a magnetic core assembly 5and two switching circuits 21. The two metallic winding assemblies 4 arewound along the same direction. The magnetic core assembly 5 includes anupper core 51, a lower core 52, two lateral legs 53 and a middle leg 54.The two lateral legs 53 are arranged between the upper core 51 and thelower core 52. In the embodiment as shown in FIG. 7, the two laterallegs 53 are connected with two ends of the lower core 52, respectively.Alternatively, the two lateral legs 53 are connected with two ends ofthe upper core 51, respectively. Alternatively, the two lateral legs 53are individually arranged between the upper core 51 and the lower core52. Moreover, the middle leg 54 is arranged between the upper core 51and the lower core 52, and arranged between the two lateral legs 53. Inthis embodiment, the metallic winding assemblies 4 are aligned with thecorresponding lateral legs 53, respectively. Consequently, the magneticcore assembly 5 and the two metallic winding assemblies 4 arecollaboratively formed as two inductors L. Moreover, the directions ofthe DC magnetic fluxes flowing through the two lateral legs 53 areidentical.

In this embodiment, the two switching circuits 21 are disposed on thefirst surface 31 of the first circuit board 3. The two switchingcircuits 21 are located beside a first side of the upper core 51 andarranged along the same direction.

In some embodiments, the voltage regulator module is fixed on andelectrically connected with a system board or a carrier board, and aplurality of conductive pads are disposed on the second surface of thefirst circuit board so as to be fixed on and connected with the systemboard or the carrier board. The plurality of conductive pads correspondto the plurality of contact pads in order to receive electric energy orsignals from the plurality of contact pads or transmits the electricenergy or signals to the system board or the carrier board.

Please refer to FIGS. 8 and 9. FIG. 8 is a schematic perspective viewillustrating the structure of a voltage regulator module according to athird embodiment of the present disclosure. FIG. 9 is a schematicexploded view illustrating the structure of the voltage regulator moduleas shown in FIG. 8 and taken along another viewpoint. In comparison withthe first embodiment, the voltage regulator module 2 b of thisembodiment further includes a plurality of conductive pads, which aremetal bars or metal blocks. For example, the plurality of conductivepads include a positive output conductive pad 75, at least one negativeoutput conductive pad 76, at least one positive input conductive pad 77and a plurality of signal conductive pads 78. The positive outputconductive pad 75, the at least one negative output conductive pad 76,the at least one positive input conductive pad 77 and the plurality ofsignal conductive pads 78 are disposed on the second surface 32 of thefirst circuit board 3. The conductive pads (i.e., the metal bars or themetal blocks) are made of copper, copper alloy or any other appropriatemetallic material with high thermal conductivity and low thermalresistance. Preferably but not exclusively, the conductive pads (i.e.,the metal bars or the metal blocks) have circular shapes, rectangularshapes, square shapes, oval shapes or hollow rectangular shapes.

The voltage regulator module 2 b is electrically connected with thesystem board (not shown) through the plurality of conductive pads on thesecond surface 32 of the first circuit board 3 (e.g., the positiveoutput conductive pad 75, the at least one negative output conductivepad 76, the at least one positive input conductive pad 77 and theplurality of signal conductive pads 78). The positive output conductivepad 75 is disposed on the first positive output contact pad 71. Theelectric energy received by the positive output terminal Vo+ istransmitted to the system board through the positive output conductivepad 75. The at least one negative output conductive pad 76 is disposedon the corresponding first negative output contact pad 72. The electricenergy received by the negative output terminal Vo− is transmitted tothe system board through the at least one negative output conductive pad76. The at least one positive input conductive pad 77 is disposed on thecorresponding at least one first positive input contact pad 73. Theelectric energy received by the positive input terminal Vin+ istransmitted to the system board through the at least one positive inputconductive pad 77. The signal conductive pads 78 are disposed on thecorresponding first signal contact pads 74. The signals received by thesignal terminals are transmitted to the system board through the signalconductive pads 78.

In some embodiments, the plurality of conductive pads (e.g., thepositive output conductive pad 75, the at least one negative outputconductive pad 76, the at least one positive input conductive pad 77 andthe plurality of signal conductive pads 78), the input capacitors 70 andthe lower core 52 are coplanar. Consequently, the second surface 32 ofthe first circuit board 3 of the voltage regulator module 2 b can bemounted on the system board more smoothly.

In some embodiments, the voltage regulator module is furtherencapsulated. Consequently, the problem of causing shift or detachmentof the voltage regulator module will be overcome.

Please refer to FIGS. 10 and 11. FIG. 10 is a schematic perspective viewillustrating the structure of a voltage regulator module according to afourth embodiment of the present disclosure. FIG. 11 is a schematicexploded view illustrating the structure of the voltage regulator moduleas shown in FIG. 10 and taken along another viewpoint. In comparisonwith the third embodiment, the voltage regulator module 2 c furtherincludes a first molding compound layer 81 and a second molding compoundlayer 82. The first molding compound layer 81 is disposed on the firstsurface 31 of the first circuit board 3. The switching circuits 21, theupper core 51 of the magnetic core assembly 5 and electronic componentson the first surface 31 of the first circuit board 3 (see FIG. 8) areencapsulated by the first molding compound layer 81. The second moldingcompound layer 82 is disposed on the second surface 32 of the firstcircuit board 3. The input capacitors 70, the positive output conductivepad 75, the at least one negative output conductive pad 76, the at leastone positive input conductive pad 77, the plurality of signal conductivepads 78 and electronic components on the second surface 32 of the firstcircuit board 3 (see FIG. 9) are encapsulated by the second moldingcompound layer 82. It is noted that numerous modifications andalterations may be made while retaining the teachings of the disclosure.In another embodiment, the voltage regulator module includes one of thefirst molding compound layer 81 and the second molding compound layer82.

Moreover, after the input capacitors 70, the positive output conductivepad 75, the at least one negative output conductive pad 76, the at leastone positive input conductive pad 77, the plurality of signal conductivepads 78 and electronic components on the second surface 32 of the firstcircuit board 3 are encapsulated by the second molding compound layer82, the second molding compound layer 82 is polished. Consequently, asurface of the positive output conductive pad 75, a surface of thenegative output conductive pad 76, a surface of the positive inputconductive pad 77 and a surface of the signal conductive pad 78 areexposed to the surface of the second molding compound layer 82.Moreover, a plurality of electroplated patterns are formed on thesurface of the second molding compound layer 82 by an electroplatingprocess. The plurality of electroplated patterns are aligned with thecorresponding conductive pads that are exposed to the surface of thesecond molding compound layer 82. For example, a first electroplatedpattern 75 a is formed on the exposed surface of the positive outputconductive pad 75 and used as the positive output terminal Vo+ of thevoltage regulator module 2 c, a second electroplated pattern 76 a isformed on the exposed surface of the negative output conductive pad 76and used as the negative output terminal Vo− of the voltage regulatormodule 2 c, a third electroplated pattern 77 a is formed on the exposedsurface of the positive input conductive pad 77 and used as the positiveinput terminal Vin+ of the voltage regulator module 2 c, and a fourthelectroplated pattern 78 a is formed on the exposed surface of eachsignal contact pad 78 and used as the signal terminal of the voltageregulator module 2 c.

It is noted that the number of the electroplated patterns and thepositions of the electroplated patterns are not restricted. That is, thenumber of the electroplated patterns and the positions of theelectroplated patterns may be varied according to the practicalrequirements. As the area of the electroplated pattern is increased, theweldable area of the voltage regulator module 2 c is increased.Consequently, when the voltage regulator module on the system boardundergoes a reflow soldering process, the inner components of thevoltage regulator module 2 c to be reheated are not detached or shifted.In other words, the current density of the solder joint is largelyreduced, and the reliability of the product is largely enhanced.

For mounting the first circuit board of the voltage regulator module onthe system board more smoothly, the voltage regulator module may bemodified. For example, a plurality of concave structures are formed onthe first circuit board for receiving the input capacitors and themagnetic core assembly. Consequently, the contact pads, the inputcapacitors and the magnetic core assembly are coplanar. Under thiscircumstance, it is not necessary to form the conductive padscorresponding to the contact pads.

Please refer to FIGS. 12 and 13. FIG. 12 is a schematic perspective viewillustrating the structure of a voltage regulator module according to afifth embodiment of the present disclosure. FIG. 13 is a schematicexploded view illustrating the structure of the voltage regulator moduleas shown in FIG. 12. In comparison with the first embodiment, the firstcircuit board 3 of the voltage regulator module 2 d of this embodimentfurther includes a first concave structure 34 and at least one secondconcave structure 35. The first concave structure 34 is concavely formedon the second surface 32 of the first circuit board 3. Particularly, thefirst concave structure 34 is a concave structure on the second surface32 of the first circuit board 3. The first concave structure 34 is incommunication with the second openings 321. The first concave structure34 is separated from the accommodation spaces 33. Moreover, the firstconcave structure 34 and the accommodation spaces 33 are located atdifferent levels with respect to the first circuit board 3. The lowercore 52 of the magnetic core assembly 5 is disposed within the firstconcave structure 34. Moreover, the depth of the first concave structure34 is greater than or equal to the thickness of the lower core 52 of themagnetic core assembly 5. Consequently, the lower core 52 is coplanarwith the second surface 32 of the first circuit board 3, or the lowercore 52 is not protruded over the second surface 32 of the first circuitboard 3. Under this circumstance, the contact pads on the second surface32 of the first circuit board 3 (i.e., the first positive output contactpad 71, the at least one first negative output contact pad 72, the atleast one first positive input contact pad 73 and the plurality of firstsignal contact pads 74) can be in close contact with the system board.The at least one second concave structure 35 is located beside the firstconcave structure 34 and concavely formed on the second surface 32 ofthe first circuit board 3. In this embodiment, the first circuit board 3includes two second concave structures 35 located beside two oppositesides of the first concave structure 34. The at least one second concavestructure 35 is separated from the accommodation spaces 33. Moreover,the at least one second concave structure 35 and the accommodationspaces 33 are located at different levels with respect to the firstcircuit board 3. The at least one input capacitor 70 is disposed withinthe corresponding second concave structure 35. Moreover, the depth ofthe second concave structure 35 is greater than or equal to thethickness of the input capacitor 70. Consequently, the input capacitor70 is coplanar with the second surface 32 of the first circuit board 3,or the input capacitor 70 is not protruded over the second surface 32 ofthe first circuit board 3. Under this circumstance, the contact pads onthe second surface 32 of the first circuit board 3 can be in closecontact with the system board. It is noted that numerous modificationsand alterations may be made while retaining the teachings of thedisclosure. In another embodiment, the voltage regulator module includeseither first concave structure 34 or the second concave structure 35.

For mounting the first circuit board of the voltage regulator module onthe system board more smoothly, the voltage regulator module furtherincludes a second circuit board. The second circuit board is fixed onand electrically connected with the system board.

Please refer to FIGS. 14 and 15. FIG. 14 is a schematic exploded viewillustrating the structure of a voltage regulator module according to asixth embodiment of the present disclosure. FIG. 15 is a schematicexploded view illustrating the structure of the voltage regulator moduleas shown in FIG. 14 and taken along another viewpoint. In thisembodiment, the voltage regulator module 2 e includes a first circuitboard 3, at least one metallic winding assembly (not shown), a magneticcore assembly 5 and a second circuit board 9. In comparison with thefirst embodiment, the voltage regulator module 2 e further includes thesecond circuit board 9. Component parts and elements corresponding tothose of the first embodiment are designated by identical numeralreferences, and detailed descriptions thereof are omitted. The secondcircuit board 9 includes a first surface 91 and a second surface 92,which are opposed to each other. The first surface 91 of the secondcircuit board 9 is located beside and in contact with the second surface32 of the first circuit board 3. The second circuit board 9 is connectedwith the system board through the second surface 92. The area of thesecond circuit board 9 is less than or equal to the area of the firstcircuit board 3. When the second circuit board 9 is fixed on the firstcircuit board 3, the edge electroplated regions of the second circuitboard 9 can provide the lateral wetting capability. Consequently, thestrength of fixing the second circuit board 9 on the first circuit board3 is increased, the complexity of fixing the second circuit board 9 onthe first circuit board 3 is reduced.

The second circuit board 9 further includes a first receiving recess 951and two second receiving recesses 952. The first receiving recess 951runs through the second circuit board 9. When the second circuit board 9is in contact with the first circuit board 3, the lower core 52 of themagnetic core assembly 5 is accommodated within the first receivingrecess 951. The horizontal size of the first receiving recess 951 isgreater than or equal to the horizontal size of the lower core 52. Thetwo second receiving recesses 952 run through the second circuit board9. The two second receiving recesses 952 are located beside two oppositesides of the first receiving recess 951. When the second circuit board 9is in contact with the first circuit board 3, the input capacitors 70are accommodated within the corresponding second receiving recesses 952.The horizontal size of the second receiving recess 952 is greater thanor equal to the overall size of the input capacitors 70 within thesecond receiving recesses 952.

In some embodiments, some other electronic components (e.g., capacitors,resistors, power components, chips, magnetic elements or mechanicalcomponents) are accommodated within the first receiving recess 951 andthe second receiving recesses 952.

The voltage regulator module 2 e further includes a second positiveoutput contact pad 931, at least one second negative output contact pad932, at least one second positive input contact pad 933 and a pluralityof second signal contact pads 934. The second positive output contactpad 931, the at least one second negative output contact pad 932, the atleast one second positive input contact pad 933 and the plurality ofsecond signal contact pads 934 are disposed on the first surface 91 ofthe second circuit board 9. The second positive output contact pad 931and the first positive output contact pad 71 are aligned with and inconnect with each other. The second negative output contact pad 932 andthe corresponding first negative output contact pad 72 are aligned withand in connect with each other. The second positive input contact pad933 and the corresponding first positive input contact pad 73 arealigned with and in connect with each other. The second signal contactpads 934 and the corresponding first signal contact pads 74 are alignedwith and in connect with each other. Consequently, the second circuitboard 9 and the first circuit board 3 are combined together. Thecorresponding contact pads are connected with each other by a weldingprocess or through a conductive adhesive. Preferably but notexclusively, the contact pads have circular shapes, rectangular shapes,square shapes, oval shapes or hollow rectangular shapes.

The voltage regulator module 2 e further includes a positive outputconductive pad 941, at least one negative output conductive pad 942, atleast one positive input conductive pad 943 and a plurality of signalconductive pads 944. The positive output conductive pad 941, the atleast one negative output conductive pad 942, the at least one positiveinput conductive pad 943 and the plurality of signal conductive pads 944are disposed on the second surface 92 of the second circuit board 9. Thepositive output conductive pad 941 is electrically connected with thesecond positive output contact pad 931 through a conductive hole of thesecond circuit board 9. The at least one negative output conductive pad942 is electrically connected with the corresponding second negativeoutput contact pad 932 through the corresponding conductive hole of thesecond circuit board 9. The at least one positive input conductive pad943 is electrically connected with the corresponding second positiveinput contact pad 933 through the corresponding conductive hole of thesecond circuit board 9. Each signal conductive pad 944 is electricallyconnected with the corresponding second signal contact pad 934 throughthe corresponding conductive hole of the second circuit board 9.

Moreover, the voltage regulator module 2 e is fixed on and electricallyconnected with the system board through the conductive pads on thesecond surface 92 of the second circuit board 9 (i.e., the positiveoutput conductive pad 941, the at least one negative output conductivepad 942, the at least one positive input conductive pad 943 and theplurality of signal conductive pads 944). The conductive pads on thesecond circuit board 9 are electrically connected with the correspondingcontact pads through the corresponding conductive holes of the secondcircuit board 9.

Moreover, a plurality of edge electroplated regions are formed on thelateral wall of the second circuit board 9, the inner wall of the firstreceiving recess 951 or the inner wall of the second receiving recesses952 by an electroplating process. The edge electroplated regions areelectrically connected with the plurality of contact pads on the firstsurface 91 of the second circuit board 9 and the plurality of conductivepads on the second surface 92 of the second circuit board 9. When thesecond circuit board 9 and the first circuit board 3 are combinedtogether by a welding process, the edge electroplated regions of thesecond circuit board 9 can provide the lateral wetting capability.Consequently, the second circuit board 9 can be securely fixed on thefirst circuit board 3. Similarly, when the second surface 92 of thesecond circuit board 9 is fixed on the system board by a weldingprocess, the edge electroplated regions of the second circuit board 9can provide the lateral wetting capability. Consequently, the secondcircuit board 9 can be securely fixed on the system board. According tothis design, the voltage regulator module 2 e can be mounted on thesystem board more smoothly through the second circuit board 9 and thefabricating process of the voltage regulator module 2 e is simplified.

Please refer to FIGS. 16 and 17. FIG. 16 is a schematic exploded viewillustrating the structure of a voltage regulator module according to aseventh embodiment of the present disclosure. FIG. 17 is a schematicexploded view illustrating the structure of the voltage regulator moduleas shown in FIG. 16 and taken along another viewpoint. In comparisonwith the sixth embodiment, the input capacitors of the voltage regulatormodule 2 f are embedded in the second circuit board 9. Moreover, theinput capacitors are electrically connected with the first surface 91and the second surface 92 of the second circuit board 9 through thecorresponding conductive holes of the second circuit board 9. Moreover,the second circuit board 9 of the voltage regulator module 2 f omits thesecond receiving recess. Since the input capacitors of the voltageregulator module 2 f are embedded in the second circuit board 9, theconductive pads on the second surface 92 of the second circuit board 9(e.g., the positive output conductive pad 941, the at least one negativeoutput conductive pad 942, the at least one positive input conductivepad 943 and the plurality of signal conductive pads 944) may haveincreased areas. Consequently, the voltage regulator module 2 f can bemounted on the system board more smoothly, and the fabricating processof the voltage regulator module 2 f can be simplified. Moreover, sincethe input capacitors of the voltage regulator module 2 f are embedded inthe second circuit board 9, the areas of some contact parts on the firstsurface 91 of the second circuit board 9 can be increased. Consequently,the contact area between the first circuit board 3 and the secondcircuit board 9 is increased.

In the above embodiment, the second circuit board 9 is applied to thefour single-phase buck circuits. In some other embodiments, the secondcircuit board 9 is applied to two-phase buck circuit or multi-phase buckcircuit. The locations of the first receiving recess, the secondreceiving recess, the plurality of conductive pads and the plurality ofcontact pads may be determined according to the location of the magneticcore assembly. The methods of installing these components are similar tothose of the above embodiments, and are not redundantly describedherein.

From the above descriptions, the present disclosure provides the voltageregulator module. The metallic winding assemblies are embedded in thecorresponding accommodation spaces of the first circuit board, and themagnetic core assembly is disposed on the first circuit board in avertical clamping manner. Moreover, one inductor is defined by themagnetic core assembly and the corresponding metallic winding assembly.In other words, a portion of the inductor (i.e., the metallic windingassembly) is disposed within the first circuit board, and the otherportion of the inductor (i.e., the magnetic core assembly) is disposedon the first circuit board. As previously described, the magneticelement of the voltage regulator module is stacked on the circuit boardof the electronic device according to the conventional technology. Sincea portion of the voltage regulator module is embedded in the circuitboard according to the technology of the present disclosure, the heightof the voltage regulator module is largely reduced.

Moreover, the metallic winding assemblies are disposed within thecorresponding accommodation spaces of the first circuit board.Consequently, the voltage regulator module can meet the requirement ofthe multi-phase buck circuit. As mentioned above, the circuit board ofthe conventional voltage regulator module is a multilayered circuitboard and a plurality of planar winding assemblies are mounted in themultilayered circuit board. Consequently, the voltage regulator moduleof the present disclosure is much thinner than the conventional voltageregulator module. Since the metallic winding assembly has lowerparasitic resistance and lower power loss than the planar windingassembly, the overall parasitic resistance and the overall power loss ofthe voltage regulator module are reduced when compared with theconventional voltage regulator module.

While the disclosure has been described in terms of what is presentlyconsidered to be the most practical and preferred embodiments, it is tobe understood that the disclosure needs not be limited to the disclosedembodiment. On the contrary, it is intended to cover variousmodifications and similar arrangements included within the spirit andscope of the appended claims which are to be accorded with the broadestinterpretation so as to encompass all such modifications and similarstructures.

What is claimed is:
 1. A voltage regulator module disposed on a systemboard, the voltage regulator module comprising: a first circuit boardcomprising a first surface and a second surface, wherein the firstsurface and the second surface of the first circuit board are opposed toeach other, and at least one first contact pad is disposed on the secondsurface of the first circuit board, wherein the at least one firstcontact pad is served as at least one of a positive output terminal, anegative output terminal and a positive input terminal of the voltageregulator module; at least one switching circuit disposed on the firstsurface of the first circuit board, wherein the at least one switchingcircuit is electrically connected with the at least one first contactpad through at least one conductive hole of the first circuit board; anda second circuit board comprising a first surface and a second surface,wherein the first surface and the second surface of the second circuitboard are opposed to each other, the first surface of the second circuitboard is located beside and in contact with the second surface of thefirst circuit board, the first surface of the second circuit boardcomprises at least one second contact pad, and the second surface of thesecond circuit board comprises at least one conductive pad, wherein theat least one second contact pad is fixed on and electrically connectedwith the corresponding first contact pad, and the at least oneconductive pad is electrically connected with the corresponding secondcontact pad through at least one conductive hole of the second circuitboard, wherein the at least one second contact pad is served as at leastone of the positive output terminal, the negative output terminal andthe positive input terminal of the voltage regulator module, and the atleast one conductive pad is served as at least one of the positiveoutput terminal, the negative output terminal and the positive inputterminal of the voltage regulator module.
 2. The voltage regulatormodule according to claim 1, wherein the first surface of the firstcircuit board comprises at least one first opening, the second surfaceof the first circuit board comprises at least one second opening, andthe first circuit board further comprises at least one accommodationspace, wherein the at least one accommodation space is formed within thefirst circuit board and arranged between the first surface and thesecond surface of the first circuit board, and the at least oneaccommodation space is in communication with the corresponding firstopening and the corresponding second opening.
 3. The voltage regulatormodule according to claim 2, further comprising at least one metallicwinding assembly, wherein the at least one metallic winding assembly isdisposed within the corresponding accommodation space and embedded inthe first circuit board, and each metallic winding assembly comprises athird opening, wherein the third opening is aligned with thecorresponding first opening and the corresponding second opening.
 4. Thevoltage regulator module according to claim 3, wherein the at least onemetallic winding assembly comprises a plurality of metallic windingassemblies, wherein the plurality of metallic winding assemblies arearranged along a plane, and the plane is parallel with the first surfaceand the second surface of the first circuit board.
 5. The voltageregulator module according to claim 3, further comprising a magneticcore assembly, wherein the magnetic core assembly comprises an uppercore, a lower core and at least one lateral leg, wherein the upper coreis disposed on the first circuit board through the first surface of thefirst circuit board, the lower core is disposed on the first circuitboard through the second surface of the first circuit board, the atleast one lateral leg is penetrated through the corresponding firstopening, the corresponding third opening and the corresponding secondopening, and at least one inductor is defined by the magnetic coreassembly and the corresponding metallic winding assemblycollaboratively.
 6. The voltage regulator module according to claim 5,wherein the second circuit board further comprises a first receivingrecess, wherein the first receiving recess runs through the secondcircuit board, and the lower core of the magnetic core assembly isaccommodated within the first receiving recess.
 7. The voltage regulatormodule according to claim 5, wherein the upper core has a first side anda second side opposed to each other, and the at least one switchingcircuit comprises a plurality of switching circuits, wherein portions ofthe plurality of switching circuits are located beside the first side ofthe upper core and arranged along the same direction, and the otherportions of the plurality of switching circuits are located beside thesecond side of the upper core and arranged along the same direction. 8.The voltage regulator module according to claim 5, wherein the at leastone switching circuit comprises a plurality of switching circuits, andthe plurality of switching circuits are located beside the upper coreand arranged along the same direction.
 9. The voltage regulator moduleaccording to claim 1, further comprising at least one input capacitor,wherein the at least one input capacitor is disposed on the secondsurface of the first circuit board.
 10. The voltage regulator moduleaccording to claim 9, wherein the second circuit board further comprisesat least one second receiving recess, wherein the at least one secondreceiving recess runs through the second circuit board, and the at leastone input capacitor is accommodated within the at least one secondreceiving recess.
 11. The voltage regulator module according to claim 1,further comprising at least one input capacitor, wherein the at leastone input capacitor is embedded in the second circuit board.
 12. Thevoltage regulator module according to claim 1, wherein the at least onefirst contact pad includes a first positive output contact pad, at leastone first negative output contact pad, at least one first positive inputcontact pad and a plurality of first signal contact pads, and the atleast one second contact pad includes a second positive output contactpad, at least one second negative output contact pad, at least onesecond positive input contact pad and a plurality of second signalcontact pads, wherein the second positive output contact pad and thefirst positive output contact pad are fixed on and connected with eachother, the at least one second negative output contact pad and thecorresponding first negative output contact pad are fixed on andconnected with each other, the at least one second positive inputcontact pad and the corresponding first positive input contact pad arefixed on and connected with each other, and each second signal contactpad and the corresponding second signal contact pads are fixed on andconnected with each other.
 13. The voltage regulator module according toclaim 12, wherein the at least one conductive pad comprises a positiveoutput conductive pad, at least one negative output conductive pad, atleast one positive input conductive pad and a plurality of signalconductive pads, wherein the positive output conductive pad, the atleast one negative output conductive pad, the at least one positiveinput conductive pad and the plurality of signal conductive pads arerespectively connected with the second positive output contact pad, thecorresponding second negative output contact pad, the correspondingsecond positive input contact pad and the corresponding second signalcontact pads through corresponding conductive holes of the secondcircuit board.
 14. The voltage regulator module according to claim 1,wherein an area of the second circuit board is less than or equal to anarea of the first circuit board.
 15. The voltage regulator moduleaccording to claim 1, wherein the second circuit board comprises aplurality of lateral walls, and the plurality of lateral walls arearranged between the first surface and the second surface of the secondcircuit board and arranged around the first surface and the secondsurface of the second circuit board, wherein at least one of theplurality of lateral walls comprises an electroplated region, and theelectroplated region is electrically connected with the correspondingsecond contact pad and the corresponding conductive pad.
 16. The voltageregulator module according to claim 1, further comprising at least onemetallic winding assembly, wherein the at least one metallic windingassembly is embedded in the first circuit board, and a projection regionof the switching circuit on the first surface of the first circuit boardand a projection region of the corresponding metallic winding assemblyon the first surface of the first circuit board are partially overlappedwith each other.
 17. The voltage regulator module according to claim 16,wherein the first circuit board further comprises at least oneadditional conductive hole, wherein the at least one additionalconductive hole is in communication with the first surface of the firstcircuit board and the corresponding metallic winding assembly, and theat least one switching circuit is electrically connected with a firstterminal of the corresponding metallic winding assembly through thecorresponding additional conductive hole.